In conventional air conditioning/heating systems for automotive vehicles, hot air and/or cool, conditioned air is produced by one or more heat exchange devices, and thereafter discharged into the passenger compartment through an assemblage of manifolded ducts and air registers. The temperature of the discharged air generally is controlled by a single control device which operates to maintain a constant average temperature in the passenger compartment of the vehicle. Thus, air at a uniform temperature is discharged at various velocities and flow rates as established by duct sizes and register settings into various portions of the passenger compartment. A conventional air conditioning/heating system cannot provide air heated to different temperatures to selected regions of the vehicle passenger compartment.
There are occasions when the driver of a motor vehicle would prefer that warmer air were being discharged into his portion of the passenger compartment, while cooler air is being discharged toward the passenger seat; conversely, there are occasions when the passengers of a motor vehicle would prefer receiving warmer air than the driver from the air conditioning/heating system. Similarly, there are occasions when passengers in rear seating positions would prefer warm air for one and cooler air for another, different than the driver of the vehicle.
U.S. Pat. No. 4,562,957 to Nakagawa et al. discloses an air conditioning/heating system for automobiles, wherein a sidestream of air from an otherwise conventional air conditioning/heating unit is further heated by a supplemental electrical resistance heater and communicated to a discharge register on the steering column, to provide warmer air to the driver's position while less warm air is being provided to the remainder of the passenger compartment. The Nakagawa et al. design, however, cannot provide warmer air to the passenger compartment while at the same time providing lower temperature air through the sidestream air discharge register to the driver's position, nor provide air at higher and lower temperatures than the driver's preferred temperature to a plurality in a plurality of seating positions.
It would be desirable to have a multiple temperature control system, to provide either warmer air or cooler air selectively to either the passenger positions or the driver position within the passenger compartment of a motor vehicle.